1. Field of the Invention
The present invention relates to semiconductor production devices, such as CVD devices, sputtering devices, dry etching devices, etc., and relates to a method of adjusting the internal pressure and a method of processing an object of processing.
2. Description of the Background Art
FIG. 22 is a diagram showing a structure of a part of a conventional semiconductor production device. The operation of this semiconductor production device will now be described referring to FIG. 23. When an object of processing, OBJ, e.g., a semiconductor wafer, is conveyed into the atmosphere from a cassette chamber 1, or a part of the processing chamber, the internal pressure in the cassette chamber 1 is adjusted on the basis of the conventional internal pressure adjusting method shown in FIG. 23.
First, referring to step S01, at first (when the time is zero), the internal pressure of the cassette chamber 1 is evacuated by using the vacuum pump Pa with the valve V11 opened to produce a vacuum therein. The valve V12 and the gate G1 are closed.
Next, referring to step S02, the valve V11 is closed to stop the exhaust of the gas in the cassette chamber 1.
Next, referring to step S03, at time t1, the valve V12 is opened to introduce a purge gas into the cassette chamber 1.
Next, referring to step S04, it is determined on the basis of a pressure gauge PG whether the internal pressure is at atmospheric pressure.
Next, referring to step S05, suppose that the pressure gauge PG indicates atmospheric pressure. At this time, the valve V12 is closed to maintain the internal pressure in the cassette chamber 1 constant.
Next, referring to step S06, the gate G1 is opened and the object OBJ is moved from within the cassette chamber 1 into the atmosphere. This time is taken as t3 herein.
However, the conventional method has the following problem The pressure gauge PG generally indicates incorrect pressure deviating from actual pressure as it is used. FIG. 24 shows a change of the internal pressure in the case where the pressure gauge PG indicates pressure lower than actual pressure. In this case, since the pressure gauge PG indicates pressure lower than actual pressure, the pressure P+ indicted by the pressure gauge PG is higher than the actual atmospheric pressure Pt. On the other hand, FIG. 25 shows a change of the internal pressure in the case where the pressure gauge PG indicates pressure higher than actual pressure. In this case, since the pressure gauge PG indicates pressure higher than actual pressure, the pressure P- indicated by the pressure gauge PG is lower than the actual atmospheric pressure Pt. As shown in these diagrams, at time t3, when the gate G1 is opened, a large difference exists between the internal pressure and the atmospheric pressure to cause a rapid flow of gas between the cassette chamber 1 and the atmosphere. This flow of gas will cause particles in the atmosphere to flow into the cassette chamber 1, or will blow up particles in the cassette chamber 1, and then the particles will attach to the surface of the object OBJ. When a large number of particles are attached to the surface of the object OBJ, the following processes and the yield will be adversely affected.